LYOOPODIALES— LEPIDODEXDEE.T:— OMPHALOPHLOIOS. 219 



rhomboidal and acute, laterally rounded, or squarrose-rliomboidal, or often 

 reduced and truncated by compression, somewhat prominent, rounded, Avitli- 

 out caudne or corrugation, marked near tlie apex by a punctate mammilla, 

 and surmounted over or at a little distance above the middle by a large, 

 interior, more or less roundish or ovate-triangular, slightly concave, prom- 

 inent boss, at the lower verge of which is situated a transverse cicatrix, 

 probably the leaf scar; central boss of the partially decorticated stem 

 usually conspicuous, often appearing as an oval, slightly concave elevation, 

 frequentl}'- traversed by two somewhat indefinite vertical low ridges, and 

 marked between the latter by a minute central trace; or, in the impressions, 

 often appearing as convex and roundish or narrowed in either direction by 

 the partial infolding of the surrounding tissue of the bolster in the course 

 of compression; foliar cicatrices situated at or a little below the middle of 

 the bolster and on the lower border of the large boss or cushion, nearly one- 

 half the width of the bolster, of very little altitude, slightl}- raised, angular 

 or slightly crescentic, the sides slightly inclined upward, subaugular or 

 broadly crescentic above, or flatly deltoidal in the center, the lateral angles 

 being continued for a distance as diminishing ridges, which are either straight 

 and vanishing short of the margin or curving upward and blending with 

 the base of the large central boss, within which, close above the foliar 

 cicatrix, lies a smaller oval or slightly ovate boss containing- an interior 

 depression and puuctiform trace; oval boss situated upon the large boss 

 close within the ventral curve of the leaf scar, the longer, vertical axis 

 being nearly one-half the altitude of the concave field of the larger boss, 

 the horizontal diameter nearly two-thirds as long as the vertical, the lower 

 end generally obscure, nearly or quite tangent to the leaf cicatrix and" 

 either partly or wholly inclosing a minute j)unctiform mammilla, which 

 appears nearly contiguous to the foliar cicatrix and may be a part thereof; 

 interior of the oval boss occupied by an oval depression, sometimes obscure, 

 usually clearly defined, about .5 mm. within the outer border of the oval 

 boss, the interval being a flat oval zone, the upper and deeper end of the 

 depression containing a minute lunbilicate mammilla; vascular trace of 

 the leaf well developed, the lateral traces being obscure; basal appendages 

 either absent or very obscure. 



The extensive collections from the Des Moines series of Missouri, sent 

 during the last few years to the United States National Museum or the 



